It is known in push-button mechanisms of the above type to design the push-button or the elements rigidly connected to this, for example, an activating bar or a rigidly arranged planar slide with a heart-shaped cam groove in which a ball or the end of a tap-formed part runs, to obtain the bistable function when the button is depressed.
British Pat. No. 877,223, for example, describes a push-button mechanism in a ball pen in the handle of which the push-button part is formed as a sleeve whose inner cylindrical surface in the lower part is formed at a heart-shaped cam groove for cooperation with a movable ball located in the groove. Upon the first depression, the ball will run along an arcuate groove along the heart-shaped cam and assume a certain position, the sleeve being locked in the depressed position by spring action. Upon a second depression of the sleeve, the ball runs along another groove along the heart-shaped cam and the sleeve as well as the ball return to the original position.
Another similar construction of a push-button with a heart-shaped cam as a controlling element to obtain the bistable function when the button is depressed, is described in U.S. Pat. No. 3,493,705. In this construction, the heart-shaped cam is arranged on a contact slide with two oppositely located contact elements. Further examples of known push-button constructions of similar kind are represented in U.S. Pat. Nos. 3,766,346 and 3,808,388 showing a heart-shaped cam arranged on the push-button part or a part rigidly arranged to therewith.